In order not to have the chamber and the passage clogged and not to have the separated component which flows through the passage causing unacceptable wear of the rotor body by erosion, the chamber and the passage in many rotors of known centrifugal separators have a complicated shape, which they obtain by an expensive disc mill cutting operation on both the inside and the outside of the rotor body.
During operation rotors of this kind also generate sound, which in many cases exceeds the sound level which can be accepted. This is particularly the case for rotors, which rotate at a relatively high number of revolutions. An often significant part of the occurring sound is generated in chambers and passages of the mentioned kind. This sound is enhanced by the gas, usually in the form of air, which is located in the space, when during operation of the rotor, it passes the openings towards the space of the passages. The frequencies of the generated sound, the pressure waves, are controlled by the geometric shape and dimensions of the chamber and the passages.
In DE 1 298 449 a simpler design of passages of this kind in a centrifugal separator is shown. In the rotor known hereby a number of passages in the shape of circular cylindrical holes, which are distributed around the rotational axis and radially directed, connect a chamber, which is formed inside the rotor and surrounds the rotational axis, with the space outside the rotor. By designing the chamber and the passages in this manner the manufacturing cost can be reduced considerably.
However, it is very easy for gas, which is located in circular cylindrical holes of this kind, to be excited in the same manner as the gas in an organ pipe by a gas, passing by the opening of the hole and be set in oscillation and thereby generate sound at a certain frequency.